What else should I be testing?

[MarkoD]

fish i lost: clown tang, copperband butterfly, spotted sweetlips and 2 clowns.

fish that survived and that are perfectly fine are: foxface rabbitfish, coral beauty and algae blenny.

i added fish 2 weeks prior to seeing any symptoms in any of the fish.
when i added them, they all seemed pretty happy and eating. none of them seemed stressed.

i have more than enough hiding places in my tank.


the only thing that comes to mind is that i might have added to much top off water too fast. but now i have an ATO